A coupled hydro-mechanical model is presented to account for the influence of plants on the mechanical and hydrological behaviour of soil. A modified Cam-clay model is implemented in a finite element code to consider the combined effect of vegetation via root reinforcement and evapotranspiration. The model is calibrated and validated by laboratory tests on soil containing roots. A vegetated soil sample is subjected to cycles of wetting and drying. The pore pressure is measured by tensiometers installed at different depths. Numerous tests on rootreinforced and non-reinforced soil are carried out. The enhancement in soil strength is obtained by comparing the test results. The tests are simulated using the numerical model and the results are compared with the experimental data.@en